Growing potatoes in bags or containers offers a practical solution for gardeners with limited space, such as on patios or balconies, or those dealing with poor-quality soil. This method bypasses traditional in-ground cultivation, providing a controlled environment where soil conditions and nutrient levels can be managed. Cultivating potatoes in this manner simplifies the harvesting process significantly compared to digging up a garden bed. The technique centers on a vertical growth method that encourages maximum tuber development within the container.
Essential Materials and Preparation
The choice of container is the first step. Specialized fabric grow bags are effective due to their excellent aeration and drainage. A bag holding at least 10 to 15 gallons is recommended per plant to allow sufficient room for root and tuber expansion. Adequate drainage holes are mandatory in any container to prevent waterlogging, which can lead to fungal diseases and tuber rot.
The ideal growing medium must be loose, well-draining, and rich in organic matter, making a standard potting mix blended with compost an excellent choice. Heavy garden soil should be avoided because it compacts easily, restricting the movement of oxygen required by developing tubers. Potatoes are not grown from true seeds but from seed potatoes, which are small tubers selected for planting.
Before planting, seed potatoes should undergo “chitting” to encourage early sprout development. This involves placing them in a bright, cool location (50 to 60 degrees Fahrenheit) for two to four weeks. The goal is to develop short, thick, green or purple sprouts, known as “eyes,” which indicate the potato is ready for active growth.
These sturdy sprouts are preferable to the long, pale sprouts that develop in darkness, as they are less likely to break off during handling. Preparing the seed potatoes and the soil mix before the growing season ensures the plants have the best start once transferred to the bag.
Initial Planting and Hilling Technique
The planting process begins by filling the bottom of the grow bag with four to six inches of the prepared soil mixture. Place the chitted seed potatoes directly onto this layer, ensuring the most developed sprouts face upward. Plant two to three seed potatoes in a 10-gallon bag, spaced evenly to maximize future tuber growth. Cover the potatoes gently with another three to four inches of soil mix. This initial depth allows the plant to establish a robust root system before the hilling process begins.
Hilling is the technique for maximizing yield in bag-grown potatoes, as tubers form along the buried portion of the stem, known as stolons, not on the roots. When the potato plant’s foliage reaches six to eight inches above the soil line, apply the first addition of soil. This process is repeated throughout the early growing season.
During hilling, fresh soil or compost is added around the base of the plant, covering all but the top few sets of leaves. This action stimulates the plant to produce more stolons along the buried stem, which swell to form new potatoes. Repeat the process every time the foliage grows another six to eight inches, effectively raising the soil level within the bag.
The addition of soil continues until the grow bag is nearly full, leaving only a couple of inches of space at the top for watering. This layering technique encourages the plant to produce new levels of tubers vertically along the stem. Covering the developing tubers prevents exposure to light, which would cause them to turn green and produce the toxic compound solanine.
Ongoing Care and Maintenance
Maintaining consistent soil moisture is important for potatoes grown in bags, as the restricted volume of soil dries out faster than an in-ground bed. The growing medium should be kept evenly moist, similar to a wrung-out sponge, but never waterlogged, which can suffocate the roots. Checking the drainage regularly is important because excess water can lead to conditions favorable for late blight, a damaging fungal disease.
Potatoes require full sun exposure, meaning the bags should receive at least six to eight hours of direct sunlight daily for optimal tuber development. The plants are heavy feeders, necessitating regular fertilization to support vegetative growth and tuber formation. Once the plants are established, a fertilizer lower in nitrogen and higher in phosphorus and potassium is preferred.
Applying a balanced fertilizer every two to three weeks, or using a slow-release granular product at the beginning of the season, supports healthy plant structure. While bag growing limits soil-borne pests, the foliage remains susceptible to airborne pathogens like potato blight and pests such as the Colorado potato beetle. Inspecting the leaves regularly and removing any signs of damage or infestation early helps maintain plant health.
Harvesting and Curing
The reliable sign that potatoes are ready for harvest occurs when the plant’s foliage naturally begins to yellow, wither, and die back. This natural senescence indicates the plant has finished transferring energy and starches from the leaves into the underground tubers. After the majority of the foliage has died completely, wait an additional two weeks before harvesting.
This waiting period allows the potato skins to thicken and “set,” which improves their storage life. For those who wish to enjoy “new potatoes” (small, tender, thin-skinned tubers), a small amount can be gently dug from the sides of the bag several weeks before the foliage dies back. Harvesting the main crop from a grow bag is easy; simply tip the entire bag over onto a tarp or the ground.
The potatoes are easily picked from the loose soil mix, minimizing the chance of damage from a digging fork or shovel. After harvesting, the potatoes must be cured, a process that strengthens the skin and heals any minor scrapes or bruises. Curing involves placing the potatoes in a dark, well-ventilated area with high humidity (ideally 50 to 60 degrees Fahrenheit) for about ten days.
This curing period ensures the potatoes are properly prepared for long-term storage in a cool, dark location, allowing them to remain viable for several months. Properly cured potatoes resist moisture loss and are less susceptible to rot.